Heat transfer from active high drop regulator

Details Heat transfer from active high drop regulator Heat transfer from active high drop regulator

2000-03-21

2001-06-19

Nguyen, Matthew (Department: 2838)

Electricity: power supply or regulation systems

Output level responsive

Using a three or more terminal semiconductive device as the...

C323S907000

Reexamination Certificate

active

06249109

ABSTRACT:

BACKGROUND OF THE INVENTION
Communications devices, such as mobile phones, pagers and the like, are getting smaller and smaller while the demands for added features are expanding. More and more components need to be packed into a smaller envelope. The need to dissipate residual heat from the components is an ever increasing challenge.
In particular, steps must be taken to avoid the overheating of integrated circuits used in these devices to maintain acceptable performance levels. A special temperature issue has arisen in communication devices, in which the voltage required by digital microprocessor controllers has dropped, while battery voltage remains the same. This drop in required voltage causes an increase in the voltage drop which must be accommodated in integrated circuit regulators. With the advent of higher data rates, increase in current consumption will be experienced with a further increase in the heat generated. There is a need, therefore, to prevent the regulator from exceeding its temperature limits without increasing the physical size of the printed circuit board of the device.
It is a purpose of this invention to provide a simple device for reducing the heat generated in an integrated circuit regulator used in a communications device. This is accomplished while taking into consideration the need for preserving current consumption at the low end of the battery charge cycle and while avoiding any space penalty in the printed circuit board.
SUMMARY OF THE INVENTION
In the regulator circuit of a communications device such as a mobile phone, pager, or the like, a voltage dropping component is inserted in series with the integrated circuit regulator. This serves to lower the input voltage to the regulator. The voltage dropping component may be a resistor or diode designed to provide the necessary voltage drop to maintain the regulator within its temperature limits. The resistor could take the form of a long and thin wire printed on the circuit board. Although this voltage loss is not a problem when the battery is fully charged, it may limit phone operation at the lower end of the battery charge cycle. In order to avoid this, a shunt circuit is employed to avoid the temperature limiting voltage drop at low voltage, when it is not needed. The shunt circuit may be actuated by a comparator which compares battery voltage to a predetermined minimum threshold voltage. The comparator activates a transistor or other switching means to short circuit the voltage dropping mechanism.


REFERENCES:
patent: 3869641 (1975-03-01), Goldberg
patent: 4751524 (1988-06-01), Balchunas
patent: 4868997 (1989-09-01), Smock et al.
patent: 5428682 (1995-06-01), Apfel

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